In order to meet the high requirement of an IMT-Advanced (International Mobile Telecommunications-Advanced) system for system capacity, it is necessary to find an available wideband spectrum in a high frequency band, but the signal transmission in the high frequency band generally has the defects of great path loss and penetration loss, so that an LTE-A (LTE-Advance) system uses a relay (Relay) technology to improve system capacity and coverage.
The relay technology is to divide a radio link between an eNB and a terminal into two links, namely, a radio link between the eNB and an RN and a radio link between the RN and the terminal, so that there is an opportunity to replace one link of poor quality with two links of good quality, so as to obtain higher link capacity and coverage. With the LTE-A as an example, an RN (Relay Node) accesses a network via a donor eNodeB (DeNB); the RN supports a user equipment (User Equipment, UE) of the LTE (Long Term Evolution, long term evolution) system; as seen from the LTE UE, the RN is equivalent to an LTE eNB, and an interface between the RN and the eNB is a Un interface, and an interface between the terminal and the RN is a Uu interface.
In order to avoid self-interference, the RN generally cannot send and receive signals in the same frequency band, so that a Un subframe of the RN generally includes two parts: One is a control part for sending a signal to the terminal and another is a data part for receiving a signal sent by the eNB. Therefore, the Un subframe needs to be transmitted on the Uu interface and the Un interface. As from the view of the terminal of the RN, the RN is an eNB, and the Un subframe configuration on the Un interface is a multicast broadcast single frequency network (Multicast Broadcast Single Frequence Network, MBSFN) subframe configuration on the Uu interface. In an LTE system in the prior art, the eNB notifies the terminal of the MBSFN subframe configuration by means of system information, so that in a relay system, the MBSFN subframe configuration is notified between the RN and the UE by means of system information. The system information may be divided into a master information block (MasterInfomationBlock, MIB) and a system information block (SystemInfomationBlock, SIB). When the Un subframe configuration is to be changed, accordingly the RN needs to notify, by means of system information, the UE of the change of the subframe configuration on the Uu interface (as from the view of the terminal, that is a change of the MBSFN subframe configuration). In addition, in the prior art, most of system information modification periods of the eNB are configurable, and the system information modification periods are configured in system information.
In the prior art, the eNB needs to notify its terminal of the update of the system information, and meanwhile, broadcast updated system information to the terminal at a next system information modification period boundary. Therefore, for the RN, when obtaining the Un subframe (re)configuration, the RN can execute the Un subframe (re)configuration only after a certain period. Specifically, the period is a system information modification period of the eNB and a system information modification period of the RN.
The prior art has at least the following problem: because the eNB and the RN use respective system information modification periods and the system information modification period of the RN, the Un subframe configuration time of the RN cannot be determined.